[unreadable] The proposed research involves the development of an efficient, portable, personal digital assistant (PDA) to assist physicians and other medical personnel assess pain. Item response theory (IRT) and computerized adaptive testing (CAT) are the core technologies that will enable a more accurate and efficient administration of pain questionnaires. In Phase I, IRT will be used to perform a statistical study of questionnaire item performance as it relates to the underlying respondent traits. All necessary tests of IRT assumptions and assessments of model fit will be performed as part of the Phase I work. The Phase I feasibility study will be a precursor to a Phase II implementation of a CAT-driven prototype that optimizes the efficiency of pain assessment via administration of a minimum number of appropriate items. [unreadable] [unreadable] Important potential benefits from IRT include greater accuracy and precision in pain assessment than is possible using conventional measures. Classical test theory has imposed barriers to effective pain assessment due to "test-dependency", "sample dependency", and the need for strictly parallel test forms. In contrast, IRT allows separation of patient underlying traits from the characteristics of particular questionnaire and scale. [unreadable] [unreadable] [unreadable]